Idiopathic Multicentric Castleman Disease With Severe Eosinophilia and Diffuse Centrilobular Nodule-A Rare Case Report.

Rationale: Idiopathic multicentric Castleman disease (iMCD), also known as angiofollicular lymph node hyperplasia, is a rare inflammatory lymphoproliferative disease with diverse clinical presentations. We report a rare case of iMCD accompanied by severe eosinophilia and diffuse centrilobular pulmonary nodules, which have rarely been previously documented in the literature. Patients’ Concerns: A 69-year-old man presented with intermittent fever, dry cough, and shortness of breath. Laboratory examination revealed severe eosinophilia. Chest computed tomography (CT) revealed bilateral pulmonary interstitial nodules and enlarged lymph nodes in the right axilla and mediastinum. Diagnosis: Axillary lymph node biopsy revealed partial atrophy of lymphoid follicles with hyaline vessel insertion and partial hyperplasia. The hyperplastic mantle zones were composed of concentric rings of small lymphoid cells. Additionally, numerous plasma cells and eosinophils were observed infiltrating between the follicles. The patient was ultimately diagnosed with iMCD with eosinophilia. Other potential causes of eosinophilia, including infections, malignancies, and other inflammatory conditions, were excluded. Intervention: The patient declined cytotoxic chemotherapy and was treated with oral methylprednisolone (40 mg/day), which was gradually tapered to 10 mg/day. Outcomes: The patient's symptoms, including fever, cough, and dyspnea, improved markedly. The eosinophil count returned to normal, and inflammatory cytokine levels (IL-1β, IL-8, IL-6, and TNF-α) decreased significantly. Lessons: This case highlights a rare presentation of iMCD with eosinophilia and pulmonary involvement, emphasizing the importance of early recognition and timely corticosteroid therapy. Our report adds to the limited data on iMCD with eosinophilia and may help inform future clinical management.